1. Field of the Invention
The present invention relates to a method for rapidly mixing at least two kinds of fluids in a micro-fluidic device which uses centrifugal force.
2. Description of the Related Art
In a micro-fluidic device such as a lab-on-a-chip in which microliter or nanoliter of fluids are treated, different shapes of chambers for performing various reactions and channels through which fluids flow are arranged. In the micro-fluidic device, a fluid usually has a low Reynolds number. At a low Reynolds number, laminar flow occurs, and thus a process of introducing at least two kinds of fluids into the micro-fluidic device and mixing them cannot rapidly be performed. This is true for micro-fluidic devices using centrifugal force (e.g., devices having a CD-shaped substrate) to drive fluid flow within the device.
U.S. Pat. No. 6,919,058 discloses a CD-shaped micro-fluid treatment substrate for rapidly mixing fluids including a micro-cavity in which two fluids meet, and a mixing channel which curvedly extends from the micro-cavity. However, there is difficulty to integrate the micro-fluid treatment substrate into micro-fluidic devices since the mixing channel occupies too large volume of space. Also, as the number of fluids to be mixed increases, the size of the micro-fluid treatment substrate needs to be increased.
Meanwhile, a method of rapidly mixing fluids including introducing a plurality of magnetic beads into fluids and inducing the magnetic beads movement using magnetic force while rotating the micro-fluid treatment substrate is disclosed in Grumann et al., Batch-mode Mixing On Centrifugal Microfluidic Platforms, LAB CHIP, vol. 5, pp. 560˜565, 2005. However, this method requires an introduction of magnetic beads into the device and an appropriate arrangement of magnets to move or vortex the magnetic beads.